Scientists in Australia are reporting an exciting breakthrough in the realm of pain-relief, demonstrating the viability of a new type of pain-blocking neuron derived from human stem cells for the first time. If the findings can be translated from mice to humans, the hope is this new therapy could come to offer a safer, less addictive alternative to opioid-based pain relievers, with the ability to target only affected parts of the body and keep side effects to a minimum.
The breakthrough comes from scientists at the University of Sydney, who are working to develop advanced treatments for what is known as neuropathic pain. This refers to the sensitivity and pain felt from typically harmless stimuli following a nerve injury, and for a lot of sufferers, there is no simple way to alleviate the discomfort.
"Nerve injury can lead to devastating neuropathic pain and for the majority of patients there are no effective therapies," says study author Professor Greg Neely. "This breakthrough means for some of these patients, we could make pain-killing transplants from their own cells, and the cells can then reverse the underlying cause of pain."
The work stems from earlier research in which scientists were able to isolate pain-killing neurons from the brains of fetal mice, and then transplant them into mice experiencing neuropathic pain to quell its effects. Neely and his team set out to replicate this using human cells, with the Nobel-Prize-winning induced pluripotent stem cell technology providing a foundation for their work.
"To make the pain-killing neurons, we take human stem cells obtained from skin or blood cells then turned into pluripotent cells, and culture them for four weeks," Neely tells us. "Each week we change the growth factors and drugs in the culture, and after four weeks we have almost pure (95 percent) pain-killing neurons. It’s quite a straightforward procedure but stem cells are delicate so it should be done by an experienced stem cell scientist."
With these pain-killing neurons in hand, the researchers then conducted experiments on rodents to see how they fared. This involved mice suffering from neuropathic pain, who were subjected to feather-light touches on the paws. Normally, healthy mice don't mind, but after nerve injury they move their foot in response. This is the basic model, Neely explains.
"We inject these pain-killing neurons into the spinal cord of the mice, where pain perception is first processed before it goes to the brain," he says. "What we found was that injection of these pain-killing neurons blocked neuropathic pain at the spinal cord, but didn’t have any effect on mice that did not have neuropathic pain. So it’s really cool and specific therapy where one injection blocks pain and this seems to be permanent so far."
The researchers describe the breakthrough as "very exciting" and are particularly enthused by the lack of side effects in their early experiments, thanks to the ability to target only parts of the body that are in pain. Next up are further studies to verify the safety in rodents and pigs, with hopes of moving toward human sufferers of chronic pain in the next five years.
"We are already moving towards testing in humans," says Neely.
The research was published in the journal Pain.
Source: University of Sydney